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Transcript of Skeletal System Introduction. ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation....
Skeletal System
Introduction
©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL
RIGHTS RESERVED.2
• The first correct illustrations of all bones was done by Leonardo da Vinci.
• Primarily made of connective tissue.
©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL
RIGHTS RESERVED.3
The Functions of the Skeletal System
• Support of the body organs and tissues• Protection of vital organs and soft tissues• Assists in movement by providing levers for
muscles to pull on• Manufacture blood cells (Hematopoiesis)• Store mineral salts as the inorganic matrix of
bone and fat in yellow bone marrow.
The Skeletal System
• Parts of the skeletal system– Bones (skeleton)– Joints– Cartilages– Ligaments
• Divided into two divisions– Axial skeleton– Appendicular skeleton
The Axial and Appendicular Skeleton
• Axial: Forms the longitudinal part of the body• Divided into three parts– Skull– Vertebral column– Bony thorax
• Appendicular: Appendages (Everything else)
Axial and Appendicular Skeleton
Bones of the Human Body
• The adult skeleton has 206 bones• Two basic types of bone tissue– Compact bone• Homogeneous
– Spongy bone• Small needle-like
pieces of bone• Many open spaces
Figure 5.2b
©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL
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Spongy Bone
• Aka ‘cancellous’ or ‘trabecular’ bone• Trabeculae - meshwork of bone• Spongy appearance created by trabeculae• Bone marrow fills spaces between trabeculae• Weaker than compact bone but lighter
Types of Bone Cells
• Osteocytes– Mature bone cells
• Osteoblasts– Bone-forming cells
• Osteoclasts– Bone-destroying cells– Break down bone matrix for remodeling and release
of calcium
• Bone remodeling is a process by both osteoblasts and osteoclasts
©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL
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The Classification of Bones
• Long• Short• Flat• Irregular• Sesamoid – intermittent
occurrence, imbedded in tendons, nonarticular
Classification of Bones on the Basis of Shape
Figure 5.1
©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL
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Bone Markings(See textbook table 7.2 on p. 137)
• Processes - projections from the surface– spine, condyle, tubercle, trochlea, trochanter,
crest, line, head, neck• Fossae - depressions– suture, foramen, meatus, sinus, sulcus
• Functions - muscle attachment, articulation, passageways
©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL
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Bone Marrow
• Red marrow– hematopoiesis– ribs, sternum, vertebrae, pelvis
• Yellow marrow– fat storage– shafts of long bones
Classification of Bones on the Basis of Shape
Figure 5.1
Classification of BonesAre you sure you need to write this down?
• Long bones– Typically longer than wide– Have a shaft with heads at both ends– Contain mostly compact bone• Examples: Femur, humerus
More self-evident classifications of bones.
• Flat bones– Thin and flattened– Usually curved– Thin layers of compact bone around a layer of spongy
bone• Examples: Skull, ribs, sternum
• Short bones– Generally cube-shape– Contain mostly spongy bone• Examples: Carpals, tarsals